Identifying Prescription Drugs at the Crime Scene
Written by Kristi Mayo   

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Identifying drugs at the point of arrest has always been a challenge for law enforcement—but that challenge is made especially difficult with the high rate of prescription medication abuse. In a June 2013 statement given to the United States Senate, DEA deputy administrator Joseph T. Rannazzisi cited an estimated 8.0 million people aged 12 or older (3.1 percent of the population) who were current users of illicit drugs other than marijuana. Of those users, 6.1 million (2.4 percent of the population) were non-medical users of psycho-therapeutic drugs.

Moreover, the non-medical use of psychotherapeutic drugs—a classification that includes prescription-type pain relievers, tranquilizers, stimulants, or sedatives—is the second-leading category of illicit drug use among Americans 12 and older, second only to marijuana use.

“This cycle of abuse can be traced to the mistaken belief among teens and young adults that prescription medications are safer than other drugs of abuse such as heroin, cocaine, marijuana, and methamphetamine, combined with, at least initially, easy access to prescription medications,” said Rannazzisi.

That high incidence of abuse can translate to a high probability of encountering prescription medications in the field. There are thousands of abused pharmaceuticals, from Ritalin to oxycodone, and when found at the point of arrest they may have been crushed, scraped, or otherwise altered. In such cases, thumbing through a pharmaceutical desk reference or calling a poison-control center would not be beneficial. Colorimetric presumptive test kits are reliable, but do not cover the full spectrum of drugs available on the street, potentially destroy the evidence if only small amounts are available to test, and their color-coded results can be subjective (“Is it blue or is it lavender?”).

Today, most of these issues may be overcome with the accuracy and simplicity of field-portable Raman spectroscopy.

Raman spectroscopy in the field

Both in the laboratory and in the field, a Raman spectroscopy device directs a monochromatic light source (such as a laser) at a substance. This excites the molecules in the sample, which emits energy—or wavelengths of light—that can be captured and analyzed. The resulting data from the wavelengths represents the unique “signature” of the substance being sampled. That information on the unknown substance can be displayed as a graph and then compared to the graphs of other known substances.

The benefits of Raman spectroscopy include (Eckenrode et al, 2001):

  • Little or no sample preparation;
  • Raman is relatively unaffected by water, CO2, and glass;
  • Raman can penetrate transparent and translucent materials, such as plastic bags and glass vials;
  • Samples can be in many forms, including liquids, solids, powders, and solutions.

Field-portable Raman spectroscopy units carry with them a library of substances that is utilized for real-time identification of unknown samples. For example, the Mobile Field Lab-3000 (MFL-3000) from Centice Corporation currently has a library of more than 3,600 prescription drugs, illicit substances, synthetic drugs, precursors, and cutting agents. Further, the MFL-3000 can identify a street mixture (such as a narcotic and a cutting agent) and will provide the content present in the sample.

The process is fast and simple. In the case of the MFL-3000, an officer must only place the sample in the unit’s chamber; press the “analyze” button; and read the results that are available in about 30-60 seconds.

The ability to carry a device equipped with efficient speed and an extensive library into the field gives law enforcement a number of powerful advantages over traditional colorimetric test kits—including important forensic-based field intelligence. A field-portable unit that can identify cutting agents, for instance, can help investigators quickly detect patterns and pinpoint a common source of different samples.

Limitations of Raman spectroscopy

Like any analytic method, Raman spectroscopy does carry some limitations. First, Raman spectroscopy cannot be used for substances that fluoresce heavily. Fluorescence—such as that produced by heroin—can mask Raman spectra. It should be noted that Centice Corporation recently introduced a workaround for testing heroin with Raman, called Surface Enhanced Raman Spectroscopy (SERS). By dissolving a small amount of a substance in a solution, fluorescent material is removed, thus enabling Raman spectroscopy.

Second, all Raman spectroscopy systems have a limit of detection where the system is unable to recognize a minor ingredient if the amount falls below a certain level (typically 5-10%). For this reason, Raman spectroscopy will tend to produce a higher false-negative rate than colorimetric presumptive tests.

Handheld vs. “Luggable” Units

Over the last decade, a number of portable Raman spectroscopy units have been introduced to the law enforcement market for the field identification of controlled substances. Raman technology lends itself to miniaturization, so the majority of these solutions are handheld devices. However, the Centice MFL-3000 is different: it is a self-contained, portable, 20-lb. kit that is contained in a rugged Pelican case. Instead of pointing a laser at the sample, the sample is placed in the MFL-3000 chamber for analysis. Its design offers advantages over handheld units, including:

  • Laser radiation is completely contained within the unit;
  • No need to worry about holding the laser steady;
  • Unit is less vulnerable to being grabbed or kicked out of the officer’s hand by an uncooperative suspect.

In addition, the MFL-3000 utilizes a technology called “Coded Aperture Raman Spectroscopy” that allows for less-costly lasers and no moving parts for light apertures. This translates to greater reliability and consistency—and a lower price tag.

With its expansive library, the MFL-3000 can identify most FDA approved pharmaceutical substances, including controlled prescription drugs. As the non-medical use of psychotherapeutic drugs continues to proliferate, field-portable Raman spectroscopy provides a quick and efficient solution to law enforcement agencies for identifying and controlling those substances.

For More Information

To learn more about the MFL-3000 and the new product line from Centice—with prices starting at just under $5000—go to:
http://www.centice.com/centice-launches-new-affordable-products-for-drug-identification

About the Author

This e-mail address is being protected from spam bots, you need JavaScript enabled to view it is the editor of Evidence Technology Magazine.

References

Eckenrode, B.A., E.G. Bartick, S.D. Harvey, M.E. Vucelick, B.W. Wright, and R.A. Huff. “Portable Raman Spectroscopy System for Field Analysis.” FBI Forensic Science Communications. 3(4) (2001). Accessed on March 9, 2014. Retrieved from: http://www.fbi.gov/about-us/lab/forensic-science-communications/fsc/oct2001/index.htm/eknrode.htm

Rannazzisi, J.T. Presented to the United States Senate Committee on Homeland Security and Governmental Affairs, June 24, 2013. Accessed on March 9, 2014. Retrieved from: http://www.justice.gov/dea/pr/speeches-testimony/ 2013t/062413-rannazzisi-testimony.pdf

 
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